The present invention is related to water planing devices herein generally referred to a surfboard and particularly to a surfboard having a fin which stabilizes the surfboard against "pearling" due to the tail becoming airborne and the fin popping out of the water. Stabilized keels have been developed for water skis and motorized small sport water craft such as disclosed in U.S. Pat. Nos. 2,274,200 and 3,964,417, the technology therein being primarily concerned with maintaining the ski or other watercraft in upright position and in lessening unwanted cavitation effects which become material when the ski or other vehicle is pulled or otherwise power propelled. Another United States patent, U.S. Pat. No. 3,747,138, discloses hydrofoils designed "to support at least a portion of the surfboard above the surface of the water" with strictly horizontal hydrofoils on the lower extremities of struts, that is, this prior art invention is related to means to provide extreme lift or hydroplaning action, almost the reverse function to that sought by applicant.